We’ve our TB-20 ‘unserviceable’ about 40 mins from our home airfield, with full-flaps stuck deployed, and engineers not available for a few days. CB’s checked, and no physical reason obvious.
Opinions vary 50-50 on whether to ferry her back, both from pilots and home-base engineers. My feeling is procedure not in the POH, insurance would be dubious, a go-around would be a serious challenge, and barge pole comes to mind.
Would appreciate other views.
If you can get help at the location after those “few days” I think you should wait for that help.
I wouldn’t. Waiting a few days versus being a test pilot….
2greens1red wrote:
a go-around would be a serious challenge
And if that is a challenge, just imagine what the take-off will be like…
There is only one thing to consider while waiting for an engineer who knows the type and how to get at the hardware.
Assuming it isn’t mechanical, the three possible causes are the motor, the switch assembly, and the wiring. If the switch is reasonably accessible, somebody who knows aircraft electrics could help by ruling the switch out as a cause, or perhaps work around a broken microswitch to at least get the flaps retracted for a ferry flight.
With my Grumman Tiger I can retract the flaps manually(assuming it is a motor problem and the motor can turn) by rotating the motor via a rubber knob(it takes rather a long time!), are you sure you don’t have such a facility?
What a pain!
I’ve had the flaps failed up before, which happily is a non-event as we regularly practice for this.
The safest place for you is unfortunately on the ground until it’s fixed.
Where are you stuck?
Most often, it is a micro switch problem.(moving parts). If you are able to locate the switch you might be able to clean it with alcohol (after consulting maintenance) and be able to get the flaps moving again until back home. Would personally not depart with flaps fully down.
What an unfortunate situation. I had this once after I got a firm to do the ACF50 corrosion proofing; they poked one of the nozzles in the wrong place and ripped a wire off one of the microswitches. I could select only no flap or full flap, so that was ok.
TB20/21 generic landing gear circuit diagram
The motor has just two wires coming out of it, so you can retract the flaps by applying the battery power to the two wires directly, in the appropriate direction. There is no manual override. I would recommend using a small battery; say 6V (for a 12V aircraft) and/or connect it via a resistor of a few ohms, so if the motor tries to drive the wrong way it doesn’t bend anything.
I would remove the belly panel and visually check for broken wires. The wiring to the microswitches and the relays is all exposed and visible. It could also be the motor that’s failed but this is a lot less likely. It is a Renault windscreen wiper motor apparently… It could also be one of the landing gear relays. If you can find a maintenance bloke who knows about electrics (rare in the UK; most stuff is done by replacing parts until the fault goes away, even if it costs the owner thousands, and yes I know of just such a recent case) then it is fairly easy to troubleshoot with a multimeter.
A TB20 will fly with full flap (obviously) and will take off with it too, with a hard runway and lightweight. But the aircraft is unairworthy now so your insurance will be void if you do this. The one scenario where insurers tend to not pay out is where the flight was illegal before it departed.
You’re lucky it’s 40 minutes from your home field (not an international flight to get to the plane). I would most definitely wait. “A few days”is nothing in plane exploitation terms….
Something else might be wrong too.
Of course, the correct answer is to have the airplane made airworthy prior to flying it.
Or, if that is not possible, consider applying for a ferry flight permit, to ferry it with a known defect. Begin your consideration of flying the plane knowing that is has demonstrated compliance to this design requirement:
(b) 6,000 pounds or less, must be able to maintain a steady rate of climb at sea level of at least 200 feet per minute, or 5 (that is, the number of feet per minute is obtained by multiplying the number of miles per hour by five), whichever is greater, with—
(1) Takeoff power on each engine;
(2) The landing gear extended; and
(3) The wing flaps in the landing position, except that, if rapid retraction is possible with safety, without loss of altitude, and without sudden changes of angle of attack or exceptional piloting skill, they may be retracted.
I have ferried home many aircraft with defects with flight permit authority, it’s a reasonable request, particularly for this situation.
If flown gently, at a lighter weight, and with low expectations of performance, it’ll be perfectly fine to fly – a competent pilot on type won’t become a test pilot. I have ferried several types home with full flaps because a flap motor failure. A few types only have “flaps up” and “flaps down”, with flaps down being the takeoff setting, so for those types, you’re fine, it’s just going to be a slow flight home.
Otherwise, consider all the advice offered here, make your own decision, and don’t tell the internet!
